GB589644A - Improvement in pressure relief valves - Google Patents

Abstract

589,644. Relief valves. JACK & HEINTZ, Inc. Feb. 16, 1944, No. 2890. Convention date, Dec. 23, 1942. [Class 135] A pressure relief valve for fluid pressure lines comprises a casing 1 having a permanently open main conduit 3 connected in the line and also a pressure relief outlet 35, the latter being under the control of an auxiliary valve 11 which normally operates to connect a byepass conduit 22 fed through a restricted passage 20 from the main conduit with one side of the main valve, but which, when pressure in the main conduit becomes abnormal, moves to disconnect this side of the main valve from the byepass conduit and connect the latter with the other side of the main valve for moving the latter to its open position. The main valve comprises integrally connected spaced pistons 6, 7 and is loaded by a spring 8 in a chamber 28 to abut an adjustable stop 9 in a chamber 5. The auxiliary valve plunger 11 has four pistons 12, 13, 14, 15 and is loaded by a spring 16 adjustable by a knob 18. The byepass conduit 22 normally communicates with the chamber 28 by a port 25, an annular space 26 and a passage 27. When pressure becomes abnormal, the auxiliary valve is moved to the left by the pressure on its end in an extension 24 of the byepass conduit. The port 25 is immediately closed and then the piston 14 uncovers a port 36 so that the chamber 28 is vented via the port 27, the annular passage 26, the port 36 and the port 35. Simultaneously, pressure fluid is admitted to the chamber 5 via a port 29, annular spaces 10 and 30, and a port 31. When the main valve has moved so far to the left, the port 35 is connected to the main conduit 3 and thereafter the chamber 5 is vented through passages 33, 34 and both valves return to the normal position shown.